Method for producing elongated, peripherally contoured shaped blanks from a metal strip

ABSTRACT

In the method for producing from a metal strip peripherally contoured, elongated shaped blanks ( 6 ) having regions of different thickness along their length (L 1 ), starting blanks ( 3 ) are first stamped from a metal strip having a constant thickness wherein the starting blanks are arranged at interleaved positions in the longitudinal direction of the metal strip. The starting blanks are subsequently guided separately through a rolling mill ( 5 ) with a longitudinal orientation and rolled in the rolling mill ( 5 ) into shaped blanks ( 6 ) having regions of different thickness.

The invention relates to a method for producing elongated, peripherally contoured shaped blanks from a metal strip according to the features of the preamble of claim 1.

Peripherally contoured, elongated shaped blanks as a starting material for chassis parts of automobiles are known. Such chassis parts are used to produce, for example, A, B or C columns. Such components are subject to different stress in different longitudinal sections. For this reason, the wall thickness is changed in certain regions to optimally adapt to stress present at different heights while also minimizing material consumption.

In this context, it is known to unwind steel tapes from coils and guide them through rolling mills. The distance between the rollers of the rolling mills is hereby controlled so that the steel tapes passing through are provided with different thicknesses in different regions. The deformed steel tapes are subsequently guided through presses where peripherally contoured, elongated shaped blanks are stamped out and subsequently moved for additional processing.

By taking into consideration that the shaped blanks are stamped out after the steel tapes were rolled and the sectional thickness regions of the steel tapes extend over the entire width, material utilization is unsatisfactory, in particular when the shaped blanks have pronounced peripheral contours. Material waste is high.

Based on this conventional approach, it is an object of the invention to provide a method for producing peripherally contoured, elongated shaped blanks with regions of different thickness along their length, wherein material utilization of the starting material is significantly improved.

The object is solved with the invention by the features of claim 1.

According to this proposal, interleaved starting blanks with a constant thickness are initially stamped from a metal strip. The position of the initial blanks is then selected depending on their desired peripheral contours so as to optimize utilization of the metal strip. Depending on the desired contour, waste can be reduced between 10% and 30% by suitable interleaving. The economy of the process and the yield are significantly improved.

The starting blanks are stamped and subsequently guided separately through a rolling mill in their longitudinal direction and rolled into shaped blanks with regions of thickness that vary over the length of the shaped blanks. The fact that the material is elongated when the starting blanks are rolled into the shaped blanks has to be taken into account when planning the interleaved positions of the starting blanks on the metal strip.

The invention has proven to be particularly advantageous when the shaped blanks have a substantially T-shaped periphery. According to claim 2, starting blanks with a periphery having a substantially T-shaped contour are arranged with interleaved transverse or longitudinal positions in relation to the longitudinal direction of the metal strip and stamped out. The stamped-out starting blanks are then separately rolled into shaped blanks, before they are shaped in an additional contouring step into shaped bodies, such as for example A, B or C columns of an automobile chassis.

To prevent undesirable contour deviations of the finished rolled shaped blanks, the starting blanks are according to claim 3 guided through the rolling mill with an effective pretension along their longitudinal direction. This can be accomplished with suitable devices.

To take into account potential thickness tolerances in a provided metal strip, the thickness of the stamped starting blanks is measured according to claim 4 before insertion into a rolling mill. The starting blanks are then rolled in the rolling mill into shaped blanks by taking into account the measured thickness tolerances.

With the invention, starting blanks can be stamped from individual metal strips, such as sheet metal, or the stamping process can be integrated into a continuous production sequence. In this context, the features of claim 5 provide that the starting blanks are stamped from a steel tape unwound from a coil. The starting blanks are then guided through a rolling mill separately and along their longitudinal orientation, where they are rolled into shaped blanks having different thickness regions.

The invention will now be described based on an exemplary embodiment illustrated in the drawings.

FIG. 1 shows in a top view a longitudinal section of a steel tape;

FIG. 2 shows in a top view a starting blank stamped from the steel tape;

FIG. 3 shows schematically in a side view a starting blank before, during and after passage to a rolling mill;

FIG. 4 shows a top view on the illustration of FIG. 3; and

FIG. 5 shows in a top view a shaped blanks rolled from the starting blank.

In FIG. 1, the reference symbol 1 indicates a metal strip as component of a steel tape 2 of unspecified length and constant thickness D over its entire length. The steel tape 2 can be drawn from an unillustrated coil. The steel tape 2 is moved through an unillustrated stamping tool, where contoured starting blanks 3 having an essentially T-shaped periphery are stamped from the steel tape 2, as illustrated in FIG. 2. As shown in FIG. 1, the stamping operation is performed in that the starting blanks 3 are stamped out from the steel tape 2, wherein the starting blanks 3 are arranged on the steel tape 2 in an interleaved pattern oriented transverse to the longitudinal direction of the steel tape 2. The amount of residual material 4 left behind, i.e. waste material, is significantly reduced compared to a stamping operation in which the starting blanks are cut out parallel to the longitudinal direction of the steel tape 2. The planned interleaved position of the starting blanks 3 before stamping is indicated in FIG. 1 by hatching.

According to an unillustrated embodiment, the starting blanks 3 can also be arranged on the steel tape 2 so as to be interleaved in the longitudinal direction of the steel tape 2, whereafter they are stamped out.

After the starting blanks 3 are stamped out, they are guided through the roiling mill 5 with a longitudinal orientation, as shown in FIGS. 3 and 4, where they are rolled into shaped blanks 6 commensurate with the respective predefined dimensions with regions A, B, C of different thickness that vary over the length L (see also FIG. 5).

When the starting blanks 3 are rolled, they are guided through the rolling mill 5 with an effective pretension that varies in the longitudinal direction of the starting blanks 3. This is done using conventional equipment which are not illustrated in detail in the Figures.

In addition, the thickness D₁ of the starting blanks 3 is measured before their insertion in the rolling mill 5, whereafter they are rolled in the rolling mill 5 into shaped blanks 6, taking into consideration the measured thickness tolerances, as indicated in FIGS. 3 to 5.

The shaped blank 6 of FIGS. 3 to 5 is different from a starting blank according to FIGS. 2 to 4 in that the starting blank 3 has a length L that is shorter than the length L₁ of the shaped blank 6, because the starting blank 3 is elongated as a result of the rolling operation.

REFERENCE SYMBOLS

1 Metal strip 2 Steel tape 3 Starting blank 4 Residual material 5 Rolling mill 6 Shaped blank A Thickness region of 6 B Thickness region of 6 C Thickness region of 6 D Thickness of 2 D₁ Thickness of 3 L Length of 3 L₁ Length of 6 V Pretension of 3 

1.-5. (canceled)
 6. A method for producing peripherally contoured, elongated shaped blanks with longitudinal regions of different thickness from a metal strip, comprising the steps of: defining on the metal strip positions of starting blanks with an interleaved arrangement, said starting blanks having a longitudinal direction and a thickness; stamping the starting blanks out of the metal strip; rolling the stamped-out starting blanks separately along their longitudinal direction in a rolling mill to form shaped blanks having regions of different thickness along the longitudinal direction of the shaped blanks.
 7. The method of claim 6, wherein the stamped-out starting blanks have a periphery with an essentially T-shaped contour and the interleaved arrangement of the starting blanks forms one of a transverse or longitudinal pattern with respect to a lengthwise direction of the metal strip.
 8. The method of claim 6, wherein the starting blanks pass through the rolling mill with a pretension applied in the longitudinal direction of the starting blanks.
 9. The method of claim 6, and further comprising the step of: measuring the thickness of the starting blanks before insertion into the rolling mill and rolling the starting blanks in the rolling mill to form the shaped blanks by taking into consideration measured thickness tolerances.
 10. The method of claim 6, wherein the starting blanks are stamped from a metal tape unwound from a coil. 